Multisensory posture control in hip and ankle joints

Hochschulschrift

Zusammenfassung: Human control of upright stance is highly complex, involving the integration of several sensory systems and the stabilization of several body segments. An experimental simplification is to apply moderate external disturbances and to model the human biomechanics as a single inverted pendulum (SIP) rotating about the ankle joints. While many aspects of the sensory integration in human posture control can be explained with the SIP model, other aspects, such as inter-segmental coordination, require the consideration of additional degrees of freedom (DOF). This thesis proceeds from a posture control mechanism controlling a SIP model and extends it to investigate the human control of hip and ankle joints using a double inverted pendulum (DIP) biomechanical model. Five experimental studies have been conducted addressing different aspects of the sensory integration in the human hip and ankle joint control mechanisms.A first study (Double inverted pendulum model of reactive human stance control) investigated which additional aspects need to be considered when controlling a DIP model as compared to a SIP model. The study proceeded from a SIP control mechanism, referred to as disturbance estimation and compensation concept (DEC concept). It uses sensor-based reconstructions of external disturbances in a feedback control mechanism, instead of ‘raw’ sensory signals. The first study showed that the principles of the DEC concept can also be applied to control DIP biomechanics, when assuming that the ankle joints stabilize the whole-body center of mass, while the hip joints stabilize the trunk.A second study (Human hip-ankle coordination emerging from multisensory feedback control) applied the findings of the first study in a detailed investigation of human sway responses to support surface tilts across a broad spectrum of tilt frequencies and amplitudes. The study provided a model that quantitatively reproduces the observed human sway responses in hip and ankle joints and confirmed the hypothesis that the hip-ankle coordination emerges from sensory interactions during reactive balancing. A major conclusion was that combining several DEC modules in a modular control structure might be used to stabilize even more complex systems with multiple DOF.A third study (Human-like sensor fusion implemented in the posture control of a bipedal robot) focused specifically on the implementation of the DIP control model in a postural control robot. The study applied a neurorobotics approach, i.e. the re-embodiment of neural mechanisms in a real-world system with human-inspired sensors and actuators. The re-embodiment provided a ‘proof of principle’ and allowed direct comparisons between the control model and human data, as robot and humans can be tested in the same experimental setup.A fourth study (Contribution of visual velocity and displacement cues to human balancing of support surface tilt) and a fifth study (Visual contribution to human standing balance during support surface tilts) investigated the improvement of human balancing through visual cues. A major issue of the fifth study was the question, how visual position and visual velocity cues affect human sway responses. Varying visual velocity information using stroboscopic illumination showed that humans use visual position and velocity cues in functionally distinct ways. The sixth study implemented these findings into the DEC concept and showed in model simulations that visual position and velocity cues specifically improve the disturbance estimates. Taken together, this thesis investigated human upright stance using engineering tools. It proposed a posture control mechanism that allows the control of several DOF and the inclusion of visual cues

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Universität Freiburg, Dissertation, 2015

Classification and Topics

• Keyword: Bewegungsapparat ; Haut

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2015
• Creator: Hettich, Georg
• Contributor: Gollhofer, Albert

Further information

• DOI: 10.6094/UNIFR/10181
• URN: urn:nbn:de:bsz:25-freidok-101813
• Rights: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:43 PM CET